Multimorbidity greatly increases the risk of hospitalization and mortality among older HF patients. Certain dyads of chronic medical conditions are particularly prevalent in HF patients and place these individuals at substantially greater risk of subsequent morbidity and mortality. Chronic lung disease and chronic kidney disease are especially common, and among Medicare beneficiaries hospitalized with HF, these conditions are among the comorbidities that confer the highest excess mortality risk. This application responds to RFA-AG-13-003 (Secondary Analyses of Comparative Effectiveness, Health Outcomes, and Costs in Persons with Multiple Chronic Conditions). An opportunity exists to study the effectiveness and safety of common treatments for patients with HF who fall into certain highly prevalent comorbidity dyad groups: HF-chronic lung disease and HF-chronic kidney disease. Under a grant from the National Heart, Lung, and Blood Institute (Management and Outcomes of Heart Failure 1RC1HL09939), we developed a rich, clinical data set to characterize contemporary practice patterns and examine rates of death and hospitalization in over 30,000 HF patients, with nearly 80% 65 years of age or older. In response to RFA-AG-13-003, our proposed study will take advantage of this existing data set to address pressing knowledge gaps about important HF subgroups and the effectiveness and safety of HF-related therapies in these high risk patients, with regard to hospitalization and death. To address these issues, our experienced research team will pursue the following specific aims: (1) to characterize two large, community-based cohorts of patients with important HF-chronic condition dyads: HF-chronic lung disease (n= >12,000) and HF-chronic kidney disease (n= ~16,000); (2) to assess the clinical effectiveness and safety associated with the use of beta-blocker therapy for patients in the HF-chronic lung disease dyad group; and (3) to assess the clinical effectiveness and safety associated with the use of ACE inhibitors/angiotensin II receptor blockers (ARBs) and aldosterone antagonists for patients in the HF-chronic kidney disease dyad group.